The joy of district cooling

Timon Singh

There's nothing like a glass of ice cold water in a hot office on a warm day, but unlike central heating systems this is a result of something arguably as important - district cooling.

Like central or district heating, district cooling delivers water to buildings, homes and factories for industrial and practical purposes, but whereas district heating delivers hot water for the winter, district cooling delivers chilled water.

This distribution of thermal energy occurs in the form of chilled water or other medium from a central source to multiple buildings through a network of underground pipes for use in space and process cooling. More often than not it is sea water, which is a cheap resource that be quickly and easily used, that is utilised for cooling industrial electrical components.

District cooling systems

District cooling systems (DCS) feature three main components to make them work - the central plant, the distribution network and the consumer system.

The central plant includes the cooling equipment, power generation and thermal storage. The distribution or piping network is often the most expensive portion of the DCS and warrants careful design to optimize its use. The consumer system would usually comprise of air handling units and chilled water piping in the building.

The cooling or heat rejection is usually provided from a central cooling plant, thus eliminating the need for separate systems in individual buildings.

As the distribution medium is usually chilled water, district cooling plants are often made up of cooling towers or heat rejection equipment.

Worldwide projects

Such systems are found the world over, but the methods are often different. In Finland, the last place you'd think they'd need things cooled, the Helsinki district cooling system uses otherwise wasted heat from summer time CHP power generation units to run absorption refrigerators for use during the summer time, cutting down on electricity usage.

As you'd expected, during the winter time, cooling is achieved simply by directly using sea water. The adoption of district cooling is estimated to reduce the consumption of electricity for cooling purposes by as much as 90 percent and an exponential growth in usage is forecast, especially in other Scandinavian countries such as Sweden.

Similar projects are occurring in the Middle East, with project management companies in the UAE diversifying their desalination and sewerage plants with the district cooling system. More than 400,000 tons of district cooling projects are already in the pipeline to provide refrigerated systems to the region and other key projects.

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